Application of antistatic/antireflective coating to a video display screen

Abstract

An antistatic/antireflective coating is applied by sputtering to the outer surface of a video display screen such as in a cathode ray tube (CRT) and is comprised of an inner antistatic layer and an outer antireflective layer. The inner antistatic layer is conductive, while the outer antireflective layer is insulative. The inner antistatic layer is deposited on the entire outer surface of the display screen, while a portion of the antistatic layer is masked during deposition of the outer antireflective layer leaving a portion, or portions, of the inner antistatic layer exposed. The exposed portion, or portions, of the antistatic layer is then electrically coupled to the CRT's grounded implosion protection, or tension, band for safely directing electrostatic charge on the display screen to neutral ground.

What is claimed is:  
     
       1. A method for applying an antistatic/antireflective coating to an outer surface of a glass display screen of a CRT, wherein a video image is produced on the glass display panel by plural electron beams incident upon a light emitting coating disposed on an inner surface of said glass display screen, and wherein an electrostatic charge is produced on said display screen by said electron beams incident thereon and incident light is reflected by said display screen, said method comprising the steps of: 
       applying an electrically conductive antistatic layer by sputtering to the outer surface of the glass display screen;  
       masking a peripheral portion of said antistatic layer; and  
       applying an insulative antireflective layer on said antistatic layer by sputtering, wherein said antireflective layer is not disposed on the masked portion of said antistatic layer leaving the masked portion of said antistatic layer exposed for connection to an electrically grounded conductor for directing electrostatic charge on the display screen to neutral ground.  
     
     
       2. The method of  claim 1  wherein the step of masking a peripheral portion of said antistatic layer includes covering opposed edge portions of said antistatic layer. 
     
     
       3. The method of  claim 2  wherein the step of masking a peripheral portion of said antistatic layer includes covering first and second opposed edge portions of said antistatic layer disposed on the outer surface of the glass display screen prior to applying said antireflective layer. 
     
     
       4. The method of  claim 1  wherein the step of masking a peripheral portion of said antistatic layer includes positioning a shield between the glass display screen and a sputtering source to prevent deposition of said antireflective layer on a selected portion, or portions, of said antistatic layer. 
     
     
       5. Apparatus for depositing an antistatic/antireflective coating on an outer surface of a glass display screen of a CRT, wherein a video image is produced on the glass display screen by plural electron beams incident upon a light emitting coating disposed on an inner surface of said glass display screen, and wherein an electrostatic charge is produced on said display screen by said electron beams incident thereon and incident light is reflected by said display screen, said apparatus comprising: 
       a sputtering system for directing an electrically conductive antistatic material onto the outer surface of the glass display screen in forming an inner antistatic layer followed by directing an insulative antireflective material onto said inner antistatic layer in forming an outer antireflective layer; and  
       a masking arrangement disposed adjacent the outer surface of the glass display screen for covering a peripheral portion of said inner antistatic layer prior to directing said insulative antireflective material onto said inner antistatic layer and preventing the directing of said antireflective material onto a portion of said inner antistatic layer in forming an exposed portion of said inner antistatic layer, wherein the exposed portion of said inner antistatic layer is adapted for coupling to a grounded electrical conductor for directing electrostatic charge on the display screen to neutral ground.  
     
     
       6. The apparatus of  claim 5  wherein said masking arrangement includes first and second shields moveable between a retracted position wherein each shield is displaced from the glass display screen and in extended position wherein each shield overlies a respective peripheral portion of the display screen. 
     
     
       7. The apparatus of  claim 6  wherein said peripheral portions are disposed adjacent opposed lateral edges of the display screen. 
     
     
       8. The apparatus of  claim 7  wherein said masking arrangement further includes first and second drive mechanisms for displacing said first and second shields, respectively, between said retracted and extended positions.